The present invention relates to an electrophotographic copier of the type including a device for the electrostatic transfer of a toner image disposed on an electrophotographic recording material to an image receiving material whose rear side is chargeable by a corona discharge device, the latter device being composed of an elongate electrically conductive shielding housing having at least one corona discharge wire clamped in an insulating manner between its ends.
German Offenlegungschrift [Laid-open Application] No. 2,649,676 discloses an adjustment device for setting the distance between such a corona discharge device and the surface of the recording material. With this device it is possible, in addition to making a first precise setting of the structurally prescribed initial distance between the various parts of the recording material surface and the corona discharge device, to also make adjustments when the machine is installed in the field in order to adapt it to changing operating conditions, such as voltage, and environmental conditions such as the ambient temperature and humidity, and fluctuations in quality of the expendable materials employed. But this known device does not permit elimination of a possible paper jam between the electrophotographic recording material and the corona discharge device. Moreover, no means are provided for removing the corona discharge device from the machine in order to clean the corona discharge device or to replace the corona wires.
German Offenlugungsschrift No. 2,321,836discloses a further electrostatic copier which includes a device for effecting a fine setting of the corona system position in order to charge a photoreceptor. The corona system can here be set so that it is capable of compensating for variations in the state of the toner, of the photoreceptor, the corona wire or the original document being copied. But this prior art device also does not include any means with which a paper jam between photoreceptor and corona discharge device can be eliminated quickly.